Using constants and parameters

Many mathematical models start with a set of definitions like the following:

 NT:= 3
 Months:= {'Jan', 'Feb', 'Mar'}
 MAXP:= 8.4
 Filename= "mydata.dat"

If these values do not change later in the model, they should be defined as constants, allowing Mosel to handle them more efficiently:

 declarations
  NT = 3
  Months = {'Jan', 'Feb', 'Mar'}
  MAXP = 8.4
  Filename= "mydata.dat"
 end-declarations

If such constants may change with the model instance that is solved, their definition should be moved into the parameters block (notice that this possibility only applies to simple types, excluding sets or arrays):

 parameters
  NT = 3
  MAXP = 8.4
  Filename = "mydata.dat"
 end-parameters

Mosel interprets these parameters as constants, but their value may be changed at every execution of a model, e.g.

 mosel exec mymodel NT=5 MAXP=7.5 Filename="mynewdata.dat"